Anaesthetic compounds



United States Patent AYAESTHETIC COMPOUNDS Arthur Ernest Wilder Smith and Emil Hofstetter, Weihusen, Switzerland, assignors to Ed. Geistlich Sohne A. G. fur Chemische/Industrie, Wolhusen, Lucerne, Switzerland, a corporation of Switzerland No Drawing. Application December 14, 1954,. Serial No. 475,282

Claims priority, application Switzerland December 22, 1953 1 Claim. (Cl. 260-294) This invention is concerned with improvements in or' relatmg to new anaesthetic compounds, and processes for their preparation;

Patented July 30, 1957 It has been found that compounds according to the present invention possess important and unexpected advantages .when compared with the compounds described in the 1 above mentioned publications, namely:

converted into their acidsalts, with for example hydro- I chloric acid, sulphuric acid, acetic acid, tartaric acid and These new compounds possess a useful pharmacological activity in thatthey represent particularly valuable local anaesthetics especially for nerve block anaesthesia.

According'to the invention there are provided new compounds of anaesthetic activity having the general formula R1 R NH-o0-c:ar-d-R= a V 1 where R 'i's' amonochlorophenyl radical or a dichlorophenyl radical which dichloropheny1 radical has at least one ChlOI'OrSllbStllllBIlt in the. metaor para-position, R is hydrogen or an alkyl group having from'one to five carbon atoms, R is an alkyl group having from one to five carbon atoms and R is a dialkylamino group' containing from two to four carbon atoms or a piperidyl or monoalkyl piperidyl group and non-toxic (as herein de-* The chlorine substituents inlthe phenyl group are pre ferably in the orthoand/ or para-positions.

The characteristic feature of the new compounds, according to the present invention resides in the halogen substituent or substituents in the phenyl radical. It is already known (see Nature vol. 170, 980 (1952) and Helv. Chem. Acta XXXVI, p. 1698, (1953)) that compounds ofzthe-type otmnn-oo onz-on-om N=( zHs):

, (m possess protracted local, z'maesthetic activity.

citric acid.

Specific preferred new compounds according to the invention are fi-diethylamino butyric acid-(p-chloro)-anilide, B-diethylamino butyric acid-(o,p-dichloro)-anilide, B-piperidyl butyric acid-(o-chloro)-anilide, fl-piperidyl butyric,acid-(m-chloroyanilide, fi-pipe'ridyl butyric acid- (p-chloro) -anilide, ,B-piperidyl butyric acid(o,p-dichloro)- anilide, and fl-piperidyl butyric acid-(2,5-dichloro)- anilide, and their non-toxic salts.

: fl-Diethylamino butyric acid-(p-chloro)-anilide hydrochloride melts at 133137 C. and is easily soluble in water;

fi-Diethylamino butyric acid-(o,p-dichloro)-anilide melts at -72" C., is recrystallizable from petroleum ether, and with acids forms salts which are easily soluble in water.

B-N-piperidyl butyric acid-(o-chloro)-anilide melts at 84-86 C., is recrystallizable from alcohol and its hydrochloride is easily soluble in water.

fi-N-piperidyl butyric acid-(m-chloro)-anilide melts at ll-5 116 C., and'is recrystallizable from acetone. It is easily soluble in dilute acids.

j- B-N-piperidyl butyric acid- (p-chloroyanilide melts at IDS-107 C., is recrystallizable from alcohol, and its hydrochloride is easily soluble in water. 7

B-N-piperidyl butyric acid-(o,p-dichloro)anilide melts at -87 Cd, and is recrystallizable from petroleum ether. With acids :it forms salts which are easily-soluble in water.

B-N-piperidyl butyric acid-(2,5-dichloro)-ani1ide melts at111=1l2fi CJ-and is recrystallizable from acetone. With acids it forms-saltswhich are easily soluble in water.

Wenow tabulate below certain of the new compounds" according to the invention, giving in each case the results obtained in vivo for their infiltration anaesthetic activity,

tissue upon administration.

Compound of formula I, where R is fiesults obtained hydrogen, R is a methyl group, and- Inflltra- Toxicity: Tissue Rls- R istion Surface LD oin irritaeflect efiect mgJkg. tion (mouse) 1 01G- EtzN- 450110.

171 2 016- n N: fg

238 a O H N: fg

Cl 4 H N- 21m.

s (HQ EtzN- fig g: o

31250. Cl H NT' +++-F lp- }(H Cl 1 Q H N: 158w.

Q 7 v 500 so.

- Compound X is the known compound of Formula II, the results for which are given for purposes of comparison only.

In the results given above for the infiltration elfect andsurface effect means weaker than, m'eans equal to, means stronger than and means termined on adult white'mice'. The toxicity: was in every.

case determined sub-cutaneously (sc.), and'in some cases also the intraperitoneal (ip.), and intravenous (-iv.) toxicity was also determined.

The tests for irritation of the tissue were carried out upon the ears of rabbits.

The results obtained are expressed as follows:

0 means no effect noticed; means a very slighteifect,

+means slight, means marked efiect and means a very strong effect.

Clinical trials upon the new anaesthetic compounds have been carried out, and it has been shown that in general their properties are fully maintainedin clinical use.

Thus, B-piperidyl butyric acid-(o,p-.dic'hloro) anilide in 2% solution, without the addition of adrenaline, has been used for the anaesthesia of the base of the tongue, the throat, the epi glottis, the glottis, -t'heand the trachea in order to permit bronchoscopy to be carried out;

The anaesthesia of mucous membrane as in bronchoscopy is a delicate matter; any substantial irritation will result in catarrhal secretion with its accompanying dangers, yet

at the same time strong anaesthetic effect is required owing to the extreme sensitiveness of the mucous membrane of the throat and bronchial passages. Using a 2% solution, of which some 2 cc. are injected intraglottaly, 2 cc. applied by spray, and between 1 and 2 cc. applied by means of brushing, it was found that in only two cases out of ten was the anaesthesia induced less than satisfactory, and in the majority of cases it was good or even excellent. The anaesthetic eifect was fully achieved only after some'S to 10 minutes, and lasted in most cases between 20-a nd 40 minutes, usually about 35 minutes. No

substantial side-effects have been observed at the dosages thus far employed. solutions have been found to be even more effective in bronchoscopy.

The new-ianaestheticcompounds according to the present invention have been applied in many fields, and have demonstrated their superior properties as compared with known local anaesthetics. 'The new compounds are particularly useful in for example dental surgery It has been found possible to prepare the new anaesthetic compounds according to the invention by reacting a compound of general'formula where R, R and R have the previously stated'm'eanings,

1 with a dialkyl amine containing from two to four carbon atoms or with piperidine' or a monoalkyl piperidine.

The reaction takes place with or without pressure at between and 200 agreeably- 0., if deit is not necessary that any additional solvent be pres- V ent, but there should preferably be a large excess of the secondary amino compound HR When the reaction has been completed this excess can be removed by distillation or in any other convenient way.

When the secondary amino compound HR has a low boiling point, as in the case of dimethylamine for example, it is convenient to efiect the reaction under pressure e. g. in an autoclave. In the case of compounds which have a comparatively high boiling point such as piperidine the reaction can also take place under pressure; it is however also convenient to carry out the reaction at normal pressures, advantageously under reflux.

The further working up of the product of the reaction takes place in any convenient way, and may for example be carried out by dissolving the crude reaction product in an acid, filtering ofi any undissolved material and precipitating the desired compound with alkali. Further purification can be achieved by repeated recrystallization from a suitable solvent, e. g. from alcohol, or of the hydrochloride or other soluble salt from water.

The present amino compounds can of course be converted into and reconverted from any desired salts thereof in any convenient way.

In order that the invention maybe well understood some preferred examples will now be described, by way of illustration only:

EXAMPLE 1 Preparation of B-diethylamino butyric acid- (p-chloro)-anilide 15 gm. of crotonic acid (p-chloro)-anilide are reacted with 100 cc. of diethylamine in an autoclave for 15 hours at 150 C. Excess diethylamine is then distilled off, and the residue poured into dilute hydrochloric acid. The solution is separated from any undissolved matter, made alkaline and extracted with ether, and the ethereal solution dried. After the ether has been evaporated ofl, the residue is taken up in absolute ether, and dry hydrochloric acid gas is passed in. A semi-solid mass of the hydrochloride precipitates, which upon trituration with ethyl acetate becomes solid.

B-Diethylamino butyric acid (p-chloro)-anilide hydrochloride melts at 133-l37 C., and is easily soluble in water. The free compound can be obtained by the action of alkalis.

EXAMPLE 2 Preparation of fl-N-piperidyl butyric acid (p-chlro)-anilide 20 gm. of crotonic acid (p-chloro)-anilide are reacted with 55 ccs. of piperidine at 150 C. in an autoclave'for hours. Excess piperidine is distilled ofi, the residue poured into dilute hydrochloric acid, and the solution separated from any undissolved matter. The clear acid solution is rendered alkaline, whereupon the new compound precipitates.

p-N-piperidyl butyric acid-(p-chloro)-anilide melts at 105-107 C., and is recrystallizable from alcohol. Its hydrochloric, sulphuric, acetic, citric and tartaric acid salts are easily soluble in water.

EXAMPLE 3 Preparation of B-N-piperidyl butyric acid- (ochl0ro)-anilide 19.5 gm. of crotonic acid-(o-chloro)-anilide are heated with 50 ccs. of piperidine at"150 C. in an autoclave for 15 hours. It is worked up as inExample 2.

p-N-piperidyl butyric acid-(o-chloro)-anilide melts at 84-86 C., is recrystallizable from alcohol, and its salts (hydrochloride, sulphate, etc.) are easily soluble in water.

EXAMPLE 4 Preparation of B-N-pipe'ridyl butyric acid-(m-chloro)- 1 anilide 20 gr'nlof crotonic acid-( m-chloro)-anilide are dissolved in 50 ccs. of piperidine and the reaction mixture is maintained for 15 hours in an autoclave at 150 C. The further working up is as in Example 2.

fl-N-piperidyl butyric acid-(m-chloro)-anilide melts at 115-116 C. and is recrystallizable from acetone. The new compound is easily soluble in dilute acids.

EXAMPLE 5 Preparation of fl-N-piperidyl butyric acid-(o,p-dichloro)- anilide 20 gm. of crotonic acid (2,4-dichloro)-anilide and 50 cos. of piperidine are maintained for 15 hours in an autoclave at 150 C. The further working up is as in Example 2.

,B-Diethylamino butyric acid (o,p dichloro) anilide melts at 70-72 C. The new compound is recrystallizable from petroleum ether, and with acids forms salts which are easily soluble in water.

EXAMPLE 6 Preparation of p-diethylamino butyric acid (0,p-dichl0r0)- anilide 20 gm. of crotonic acid (o,p-dichloro)-anilide and ccs. of diethylamine are maintained for 15 hours in an autoclave at 150 C. The further working up is as for Example 2.

fi-diethylamino butyric acid-(o,p-dichloro)-anilide melts at 7072 C. The new compound is recrystallizable from petroleum ether, and with acids forms salts which are easily soluble in water.

EXAMPLE 7 Preparation of fi-N-piperidyl butyric acid (2,5-dichl0r0)- anilide 20 gm. of crotonic acid-(2,5-dichloro)-anilide and 50 ccs. of piperidine are maintained in an autoclave for 15 hours at 150 C. Further working up as for Example 2.

fi-N-piperidyl butyric acid-(2,5-dichloro)-anilide melts at 111-112 C. and is recrystallizable from acetone. The new compound forms salts with acids, which are easily soluble in water.

EXAMPLE 8 Preparation of fl-N-piperidyl butyric acid (o,p-dichloro)- anilide 1 part of crotonic acid (2,4-dichloro)-anilide and 1.7 parts of piperidine are boiled together for 2 hours under reflux at IDS- C. Excess piperidine is then distilled oif and the remainder poured into dilute hydrochloric acid. 0n cooling the hydrochloride of the new compound precipitates.

The new compound B-N-piperidyl (o,p-dichloro)-'anilide melts at 85-87 C.

The preparation of the p-piperidyl derivative of other chlorine substituted anilides of crotonic acid and of higher cap-unsaturated acids can be carried out in an analogous manner.

We claim:

A new compound selected from the group consisting of ,B-diethylamino butyric acid-(p-chloro)-anilide, fi-diethylamino butyric acid-(o,p-dichloro)-anilide, fl-piperidyl butyric acid-(o-chloro)-anilide,'p-piperidyl butyric acid- (m-chloro)-ani1ide, fl-piperidyl butyric acid-(p-chl0ro)- anilide, B-piperidyl buty ric acid-.(QP-dichloro) -.anilide,

and ,B-piperidyl butyric acid-(2,5-dich1oro)-anilide, and

non-toxic salts of said-compounds. v c

References Cited in the file of this patent 5 FOREIGN PATENTS Great Britain Aug. 4, 1934 OTHER REFERENCES Hofstetter: Nature, volume ,170, P8ge980, Dec.- 6, 1952 :10

8 ,Hall e t:a1.:.Journa1 of the Chemical Society (London) for 1948, pp. 1909-1911, Jan. '10, 1948.

Ahmed, et al.: Journal of the Indian Chemical Society, vol. 15, pp. 152-159, abstracted in Chemical Abstracts, vol. 32, column 7040, 1938.

Gaind et aL: Journal of the Indian Chemical Society, vol. 23,pp.9-12, abstracted in Chemical Abstracts, vol. 40, col. 5709, 1946. 

